Conformable coil



J. C. BENDER ETAL CONFORMABLE COIL Filed Sept. 20, 1948 Dec. 16, 1952 John C Bender INVENTOR- ATTOR/Vf) Clarence T Bq/(zp l?/M A1411 2 11 5! llh .l\\

Patented Dec. 16, 1952 Tex assignors to HoustomOil FieldnMa-terial I Company, Inca, Houston, Tex,, a corporation of Delaware Application September 20, 1948; SerialN'o. 50,124

2-Claimsr' 1 i This invention-relates to the-testing. of materials-111:0 determine variations. or: defects: therein andiirelates more particularly to acmethodiaand means to test materials of irregular internal contour.

There are. many and numerous methods and apparatus for the testing of materials to determinelvariations. or defectsthereinr One of; these. methods consists ofmaintaining a sustained s: cillation of resonant frequency in an oscillatory circuit and successively electromagnetically coupling1different small portions of the material be? ing' tested with thecircui'twhereby changes in the electrical characteristics of the material being tested due to defects or Variati'QnethereinprQ- dime-changes in this frequency. Thesechanges maybe indicated in many ways such as by sonic or visual meal-1st Such a means and method is disclosed i'n-the patent to Dana, No'. 1,984,465, issued December 18, 1 934, as applied to electrical conductors.-

Theabove method and further-and similar ones in the art have not been used in testing materials of irregular internal contourdue to the difficulty in securing satisfactory: results inlthat an exploratory-coil inserted into internal contours of irregular configuration is limited in size by the minimum orifice therein and does not effectively electromagnetic-ally couple successive portionsof the material being tested.

It is among the objects of ourinvention to'pro vide a method. and meansto produce a radio frequency electromagnetic field with the axis and at right'-- angles to the axis of the material being tested.

It is a further obiectto provide: ameans to: pro.- duce amagnetic field which will conform to and follow thepathof the irregular internal contour of-the materia-l being testedso-that defects or variationsin the material will produce changes in an oscillatory circuit maintained at resonant frequency so that such frequency may be heterodyned with a current from an oscillating generator of constant frequency in order that the changes in beat frequency therebetween may be observed.

It is a particular object to provide an exploratory coil which will effectively and efiiciently electromagnetically couple successive portions of ferrous or non-ferrous pipe, such as internal upset pipe.

It is a particular and further object to provide an exploratory coil which may be effectively and efficiently used in electric, electromagnetic or electronic methods of inspecting ferrous or nonferrous material for defects, flaws or variations.

?,1IQ EB bearingL-SeriaI Number 50,123,, amethod and different .meanspis disclosedand claimed to accomplish the above objects.

It' is a further featureoi: our-invention; toprovide: an exploratory 00113 which. will detect-longitudinal and transverse-defects and variationsyby.

manipulation of the coil.

It-is'a. further feature of our iny'ention to proe vid'e an exploratory. coiliwhichrwil'la detect longitudinal and transverse-defects and variationsaby manipulation. of. the coil.

Other objects andedlvantages are apparent from the: following description of a preferred. errr bodiment of our: invention taken-in con-junction.

with the accompanying drawing; whereintlikelreference' numerals designate like parts throughout both views, and where! Figure 1 isalongitudin'a'l', cross-sectional. :view

of our: testing. device illustrating; thexpuse; thereof in testing internal ups p p andv Figure 2" is similar: to Figural and-illustrates,

a modification in mounting-:the-ccil unwinding.

Referring. to: Figure .1 .oftheadrawing the: nu-

meral I10 designates thepipe to'y be tested which le -internally upset at IL. The testing unit, generally designated: as v I 2 isinserted: and withdrawnas shown in the dctted lines inv lii'gurel.v

' Our-testing device comprises a flexible body member I 3; which maybe of ring-likeconfigurat'ion and formed of rubber or other suitableffexiblematerial which will yieldingly' conformtothe internal configuration of pipe Hi. The body;

member l3 may have'a radial recess i4: disposed in its periphery" in which a suitabletesting coil or winding l 5 is disposed.

' Flexible armsj wand [insecure body member l3 to guide support 1'8 and the former are outwardly bowed to aid in positioning coil [5 in axial or longitudinal position with respect to pipe 10. The end of arm I6 is outwardly turned and arms I6 and H are pivotally secured to body member [3 by means of hinge plates I9 and 20 respectively. Arm [6 is fixed to guide support l8 and arm I! is free to move longitudinally along channel 2| of guide support [8. Thus, by moving arm ll longitudinally, body member I3 may be positioned either longitudinally as shown in dotted lines or axially with respect to the interior walls of pipe Ill.

Flexible springs 22 or other means such as retractable rollers and the like may be connected to guide support It to properly center or position the testing device in the pipe [0.

An electrical connection 23 is provided to connect the coil ['5 to the particular circuit being used in testing the pipe [0. Threads 24 may be provided on the free end of guide support member It in order that a telescope may be connected thereto to visually examine any indicated flaws.

In testing an internally upset pipe for flaws or variations, our exploring coil may be inserted into the pipe It in the manner illustrated in dotted lines in Figure l. The coil and body member will readily compress and pass through the narrower opening at the joint. Flexible arm ll may be manipulated along channel 2| in guide sup port 18 to bring coil into axial position with respect to the upset portion ll of the inner walls of the pipe H] and coil [5 will thus be in close proximity thereto as indicated in Figure 1. Guide springs 22 will center the device and the coil may be urged through the pipe by means of a cord or rod not shown.

Assuming that our testing device is used in connection with an electronic circuit, the coil l5 will set up a radio frequency electromagnetic field in close proximity to the internal walls of pipe as it is moved inside the latter thereby setting up eddy currents in the internal Walls thereof and any variations or defects therein will produce changes in the frequency in the oscillatory circult to which the coil is connected thereby producing changes in the frequency of such circuit which may be indicated by suitable means to the operator. As indicated heretofore, a telescope may be attached to the threaded end 24 of member 18 in order that the operator may visually inspect the flaws or variations indicated by the exploratory coil and associated circuit and indicating means. To aid in such visual inspection a light may be provided in the device.

If desired our coil may be urged through pipe In in a longitudinal position as indicated in the dotted lines in Figure 1. By manipulation, transverse defects or flaws or variations, may be observed as described above.

A modification of our coil is illustrated in Fig ure 2. Here the flexible body member 13 is mounted on flexible fingers 25 which may be of any suitable material, such as spring steel which will yieldingly hold coil I against the interior of the pipe thereby permitting the same to conform to the internal configuration thereof. No more description of the modification is given as the other elements are the same as the above described and so is the manner of operation. In this particular modification, however, the coil may not be pivoted for longitudinal positioning inside the pipe l0.

Our coil may be used in testing fiat work or sheets, such as in rolling mills, and in such case,

the coil may be formed oblong to provide maximum surface to the material being tested. It is apparent that our coil may be used in connection will all the methods of inspection disclosed in the said co-pending application.

Many modifications in details and substitution of parts and materials may be made in our conformable coil. For example, body member l3 may be made of spring steel, and need not be recessed to receive coil [5, or the body member may be of a sponge rubber or other yielding material and may be solid if desired. Any means may be used to center our coil or to pivot thesame for positioning inside a pipe or on fiat materials. In testing materials having circular passages, fiexible connections or knuckle joints may be employed and by obvious modification our coil may be used to detect variations, flaws or deflects in materials having internal passages of varying configuration. It seems obvious that our testing device is more efficient when used in materials having consistent internal passages than those of the prior art.

We claim:

1. A device for detecting flaws in pipe comprising a ring-like member formed of flexible material adapted to yieldingly conform to the configuration of the internal passage in said pipe. a recess in the periphery of said body member, a coil disposed in said recess and adapted to set up a magnetic field in said pipe as said device is urged therethrough, and means to pivot said body member for easy passage through restricted areas in said pipe.

2. A device for finding variations and flaws in restricted internal passages in materials comprising a body member conformable to the surface of the restricted internal passages, means carried by said bodymember to produce a magnetic field whereby said means is maintained in maximum inductive relationship with said restricted internal passages, and means to pivot said body member for easy passage through restricted areas in said pipe.

JOHN C. BENDER. CLARENCE T. BAKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,041,058 Fossati May 19, 1936 2,124,579 Knerr et a1 July 26, 1938 2,194,229 Johnston et a1 Mar. 19, 1940 2,201,256 Barrett May 21, 1940 2,216,600 Moore Oct. 1, 1940 2,220,563 White Nov. 5, 1940 

